PubMed Health⌕ Search

Biomedical subjects

R B Taylor

Publications and source records attributed to R B Taylor.

At least 19 recordsLinked to original sources
PubMed1992

Prophylactic use of apraclonidine for intraocular pressure increase after Nd:YAG capsulotomies.

We evaluated the prophylactic effect of 1% apraclonidine HCl in controlling the increase in intraocular pressure after Nd:YAG posterior capsulotomy in a large, multicenter double-masked clinical trial. One hundred sixty-four patients were enrolled into the apraclonidine-treated group, and 165 into the vehicle-treated group. The incidence of increase in intraocular pressure (greater than 5 mm Hg) in the apraclonidine-treated group (7%, 11 of 163 patients) was significantly less than that in the vehicle-treated group (39%, 64 of 164 patients). Similarly, the mean maximal change in intraocular pressure in the apraclonidine-treated group (1.3-mm Hg decrease) was significantly different from the increase in the vehicle-treated group (5.3-mm Hg increase). Few adverse reactions were observed. The risk for significant loss of visual function after Nd:YAG laser posterior capsulotomy, combined with the efficacy and relative safety of prophylactic apraclonidine, suggest its addition to the treatment armamentarium.

Adrenergic alpha-Agonists↗
PubMed1992

Simultaneous determination of some antibacterial drugs in isosensitest broth using high-performance liquid chromatography with solid-phase extraction.

A method is described for the simultaneous determination of combinations of some antibacterial drugs in a matrix of isosensitest broth. A double solid-phase extraction procedure is described in which trimethoprim and dibromopropamidine isethionate together with 4-chlorophenylbiguanide as internal standard are freed from endogenous components by a cation-exchange extraction cartridge and subsequently removed and individually separated by reversed-phase ion-pair chromatography. Sulfadiazine, sulfamerazine and p-aminobenzoic acid, unretained by ion exchange, are similarly isolated for chromatography by adsorption on a CH-bonded phase cartridge and individually assayed using the same chromatographic system. The rationale of the pre-treatment and chromatography is described and the quantitative aspects of the analyses of selected combinations of these drugs are reported.

4-Aminobenzoic Acid↗
PubMed1992

Spinal stimulation to locate preganglionic neurons controlling the kidney, spleen, or intestine.

The organization of sympathetic preganglionic neurons may be a substrate for selective control of sympathetic outflow to different vascular beds. This study was done to determine the spinal segments containing preganglionic neurons controlling discharge of renal, splenic, and mesenteric postganglionic nerves. In urethan-anesthetized rats, preganglionic neurons were stimulated by microinjecting D,L-homocysteic acid (3 nl, 0.17 M) into the lateral gray matter of the third thoracic (T3) to the fourth lumbar (L4) spinal segments. Responses from all three nerves could be elicited from segments T4-T13. The greatest increases in renal nerve discharge were evoked from segments T8-T12, the largest increase of 59 +/- 9% elicited from T10. Increases in splenic and mesenteric nerve discharge were smaller and were evoked more uniformly from T4-L3. The largest increases in discharge of splenic and mesenteric nerves were 19 +/- 5% (from T5) and 26 +/- 4% (from T10), respectively. The widely overlapping spinal cord segments controlling these three organs suggest that location of the preganglionic neurons in different spinal segments is not part of the mechanism for selective sympathetic control. However, the larger renal nerve responses demonstrate that sympathetic output to these organs can be differentiated at the level of the spinal cord.

Animals↗
PubMed1991

Determination of teicoplanin in plasma using microbore high-performance liquid chromatography and injection-generated gradients.

A reversed-phase isocratic high-performance liquid chromatographic method for the determination of total teicoplanin in plasma is reported. The method developed uses a bracketing injection technique in conjunction with large injection volumes on a 1 mm diameter column to form a limited injection-generated gradient. The chromatography yields adequate resolution among all the major components for individual quantitation and also allows quantitation of total teicoplanin in plasma using ultraviolet detection. Pretreatment is by solid-phase extraction which uses C8 Bond Elut cartridges and gives effective clean up from endogenous materials. The method offers a faster and simplified means to determine total teicoplanin in plasma than those previously reported, and has a detection limit of 50 ng/ml.

Anti-Bacterial Agents↗
PubMed1991

An evaluation of the antibacterial activities of combinations of sulfonamides, trimethoprim, dibromopropamidine, and silver nitrate compared with their uptakes by selected bacteria.

Modifications of antibacterial activity have been demonstrated using combinations of two antibacterials from trimethoprim, sulfonamides (sulfadiazine, sulfamerazine, and silver sulfadiazine), silver nitrate, and dibromopropamidine isethionate, either formulated in a cream base or dissolved in peptone water. The creams were evaluated using the agar cup diffusion method in isosensitest agar. The peptone water solutions provided fractional inhibitory concentrations for combinations of the antibacterial substances. The test organisms were Pseudomonas aeruginosa, Enterobacter cloacae, and Staphylococcus aureus. Bacterial uptakes of antibacterial combinations, determined by either an HPLC assay method or an atomic absorption method, combined with dry cell weight determinations, indicated that enhancement of activity of the antibacterial combinations against P. aeruginosa (two strains) and E. cloacae were related to marked increases in the bacterial uptake of the chemical agents. Decreases in activity were related to decreased uptake of either dibromopropamidine and/or silver ions. The effect of the trimethoprim and the sulfonamides was shown to depend on their effect on bacterial folate synthesis. It is suggested that partial blockade of the folate synthetic pathway leads to an effect on cell permeability which results in increased uptake of antibacterials. Dibromopropamidine isethionate also has an effect on cell permeability which produces an increased bacterial uptake of a second antibacterial present in the medium. These findings provide further explanation of how subinhibitory concentrations of trimethoprim and sulfonamide combinations are synergistic against a wide range of bacteria even when certain bacteria are resistant to either member of the combination.

Bacteria↗
PubMed1990

Bovine gamma globulin-specific CD4+ T cells are retained by bovine gamma-globulin-tolerant mice.

Immunological tolerance is an acquired state of antigen-specific nonresponsiveness which is generally attributed to either the deletion or suppression of tolerogen-specific T helper cell clones. Unresponsiveness to xenogeneic immunoglobulins can be readily induced and has been extensively studied in order to ascertain the means by which tolerance is established and maintained. As an absence of reactivity to foreign immunoglobulin has been noted in situations where suppressor cell activity was minimized, this tolerant state has often been ascribed to clonal deletion. The present study demonstrates that bovine gamma-globulin (BGG)-tolerant mice are unable to generate humoral responses to BGG in vivo and yet harbor BGG-specific CD4+CD8- T cells which can divide and secrete interleukin 2 when stimulated in vitro. Indeed, the in vitro reactivity to BGG of these cells exceeded that of a similar population of non-immune cells. This is in direct opposition to the loss of response that would be expected if clonal deletion were operative. The presence of BGG-specific CD4+ T cells, which appear to be at least partly primed, in mice unresponsive to BGG, indicates that tolerance to BGG is likely to be dependent on unidentified immunoregulatory processes rather than clonal deletion.

Animals↗
PubMed1990

Local crime as a natural hazard: implications for understanding the relationship between disorder and fear of crime.

Local crime rates are similar in several respects to natural hazards. The points of similarity include objective and subjective features and responses to both. These comparable characteristics may help explain a continuing conundrum in the responses to disorder literature: the loose coupling between crime and fear levels at the local level. The proposed analogy may also be relevant to the relationship between local crime and behavioral responses to disorder. The points of analogy between crime and natural hazards lead to theoretical expectations supported by results from recent studies on responses to disorder. The perspective developed here helps explain why instrumental responses to crime elevate fear over time. We discuss the policy implications of the analogy, and suggest future areas of research and theoretical development.

Crime↗
PubMed1990

Determination of antibacterial agents in microbiological cultures by high-performance liquid chromatography.

A general high-performance liquid chromatographic (HPLC) procedure is described which allows the assay of several antibacterial drugs in combination in a matrix of bacterial cell cultures. The drugs assayed were dibromopropamidine, trimethoprim, sulphadiazine and sulphamerazine. It is also shown that p-aminobenzoic acid, which is an essential metabolite of many micro-organisms, does not interfere and can itself be quantified. The method uses solid-phase extraction on a cyclohexyl-bonded silica with subsequent separation of the analytes by reversed-phase HPLC. Tetrabutylammonium is used in order to reduce the retention of trimethoprim and dibromopropamidine and quantification is by ultraviolet detection at 254 nm. The analytical characteristics of the proposed method are shown for certain drug combinations.

Anti-Infective Agents↗
PubMed1990

Measurements of human bioluminescence.

In measuring the output of light from the human skin, we estimated the total photon rates to be of the order of 170-600 photons/s/cm2, depending on anatomical location. The light was strongest at the red end of the spectrum, but fell below detectable levels in the ultraviolet. Significant variations were observed between individuals in both photon rate and spectral profile. The photon rate also varied significantly with time for a single individual. The possible source of this light and its significance are discussed.

Equipment Design↗
PubMed1990

Patient profiling: individualization of hypertension therapy.

Although the stepped-care approach remains the cornerstone of antihypertensive therapy, the patient's profile must also be considered. Important issues include the patient's age, race and activity level, potential for hypertensive complications, presence of other diseases, cost of medications and probability of adherence to the recommended drug regimen. Nonpharmacologic treatment based on lifestyle changes is a useful adjunct to drug therapy, but it is not sufficient to control hypertension in most patients. Selection of pharmacologic therapy must be based on a knowledge of each drug's mode of action and side effects, as well as the characteristics of special patient populations.

Adrenergic beta-Antagonists↗
PubMed1990

The Royal Naval Medical Stores for Service Afloat: a prospective quantitative study.

The contents of the scale of Medical Stores for Service Afloat must provide adequate quantities of drugs to allow proper patient care in a variety of situations often remote from specialist support. The overall make up of the scale is difficult to envisage outside the context for which it was conceived. This study was designed to assess the accuracy of the make up of the scale in three RN ships over a six-month period during a detached deployment. During this time the usage of all consumable items was specifically recorded and the outcome subjected to rigorous analysis in relation to the present scale. The results of the study indicate that in the case of both HMS Ark Royal (AR) and the two smaller ships HMS Edinburgh and HMS Sirius (ES) the quantities of drugs in the majority of cases are in excess of requirements. Of the 290 (AR) and 266 (ES) individual drugs 68% and 40% respectively could safely be reduced by varying amounts, whereas only 7.6% and 4.9% respectively needed to be increased. Furthermore, when these changes are costed the savings that result are 7806 pounds for the AR scale and 1532 pounds for the ES scale. Extrapolation of these figures across the surface fleet produces an overall saving on the costs of drugs of over 87,000 pounds.

Cost Control↗
PubMed1990

NBCI--another threat to operational effectiveness?

Battle casualties are well recognised as a threat to Operational Effectiveness (OE) at times of conflict. Less well appreciated is that naturally occurring illnesses and injuries--Non-Battle Casualties and Injuries (NBCI)--continue to present at such times and will add to the problems of fighting the ship. This prospective study showed that NBCI resulted in a total of 1369 man days of lost personnel effectiveness among some 1738 RN servicemen during a 180 day deployment. That is just 0.42% of the possible man working days. This represents a loss of 4.3 man days per 1000 at risk per day in terms of fitness for Full Duties or 2.74/1000/day excluding those able to perform Light Duties. It is unlikely that such rates would affect the OE of the fighting units but they do represent a significant challenge to the Royal Naval Medical Service to continue to maintain the rates at such low levels, so that when aggregated to the numbers of battle casualties, OE is maintained as far as possible.

Humans↗
PubMed1989

Virulence of Mycobacterium avium complex strains from acquired immune deficiency syndrome patients: relationship with characteristics of the parasite and host.

The virulence of 24 strains of Mycobacterium avium complex (MAC) isolated from patients with acquired immune deficiency syndrome (AIDS) was assessed using the beige mouse model. Most changes in colony forming unit (cfu) counts in spleen and lungs, and spleen weights occurred between days 1 and 14, with comparatively smaller changes 14-28 days postinfection. The virulence was assessed by a score formulated from the four most useful parameters: mortality, spleen cfu, lung cfu and spleen weights at 28 days. The scores of the 24 strains showed a normal distribution; four strains falling above one standard deviation from the mean were classified as high virulent, those four falling below one standard deviation as low virulent, and the remaining 16 as of intermediate virulence. Virulence was associated with the total number of plasmids and the occurrence of large plasmids (greater than 100 MDa) in the MAC strains. There was an inverse correlation between virulence and the organism's capacity to trigger the release of oxygen metabolites from peritoneal macrophages. Macrophages from mice infected with the MAC strains of different degrees of virulence released superoxide anion (O2-) with a peak at two weeks, the peak levels bearing an inverse correlation to virulence. No association was seen between virulence and source of specimens, biochemical characteristics, drug susceptibility, serotypes or phage types.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Determination of clavulanic acid by a sensitive HPLC method.

A new HPLC method is described for the estimation of clavulanic acid. It should be of use for further studies on the penetration of clavulanic acid into body tissues and fluids. It utilizes standard HPLC equipment and UV detection, but provides at least ten-fold increased sensitivity (less than 0.008 mg/l) over previously published methods by using solid phase extraction with imidazole derivatization and subsequent pre-concentration of the sample, and a microbore chromatographic column with a conventional detection system.

Chromatography, High Pressure Liquid↗
PubMed1988

A model for regional blood flow measurements during cardiopulmonary resuscitation in a swine model.

Recent reports examining regional blood flow during cardiopulmonary resuscitation (CPR) have been criticized for several reasons: (1) cardiac arrest times of 5 min or less are not reflective of the prehospital setting, (2) anesthetic agents may significantly influence autonomic control of regional blood flow, (3) canine cardiac anatomy and coronary blood supply are not reflective of humans and (4) precise validation data for blood flow measurements have not been reported. This study presents a methodology and model for measuring regional blood flow during CPR after a prolonged cardiac arrest. Fifteen swine weighing 15-25.4 kg were instrumented for regional blood flow measurements using tracer microspheres. Regional cerebral and myocardial blood flow were measured during normal sinus rhythm (NSR) and during CPR following a 10-min cardiopulmonary arrest. Regional blood flow (ml/min/100 g) to the cerebral cortices averaged less than 3% of baseline flow (NSR: right cortex = 41.2 +/- 13.8; left cortex = 41.2 +/- 12.2; CPR: right cortex = 1.3 +/- 1.2; left cortex = 1.3 +/- 1.3). Total myocardial blood flow averaged less than 5% of baseline flow (NSR = 211.5 +/- 104.9; CPR = 9.5 +/- 14.9). The flow data demonstrates minimal cardiac and cerebral perfusion with standard CPR following a 10-min arrest. The variability in the pilot data may be used in determining sample sizes for future studies.

Animals↗
PubMed1988

Myocardial oxygen delivery/consumption during cardiopulmonary resuscitation: a comparison of epinephrine and phenylephrine.

Our study compared the effect of high-dose epinephrine with the pure alpha-agonist phenylephrine on regional myocardial blood flow (MBF), myocardial oxygen delivery (MDO2), myocardial oxygen consumption (MVO2), and defibrillation rates during CPR. Fifteen swine weighing more than 15 kg were instrumented for measurement of regional MBF using radiolabeled tracer microspheres. Measurements of regional MBF, MDO2, and MVO2 were made during normal sinus rhythm. Ventricular fibrillation was induced and persisted for ten minutes. CPR was begun using a pneumatic compression device. Regional MBF, MDO2, and MVO2 were measured during CPR. Following three minutes of CPR, animals (N = 15) were allocated to one of three groups (n = 5): Group 1, epinephrine 0.2 mg/kg; Group 2, phenylephrine 0.1 mg/kg; or Group 3, phenylephrine 1.0 mg/kg. Measurements of regional MBF, MDO2, and MVO2 were repeated after drug administration. Extraction ratios, defined as MVO2/MDO2, were calculated during normal sinus rhythm, CPR, and after drug administration. Defibrillation was attempted 3 1/2 minutes after drug administration. There was no significant difference in MBF, MDO2, MVO2, and extraction ratio during normal sinus rhythm and CPR for any of the groups. Total MBF following drug administration was 67.2 +/- 49.4 mL/min/100 g for the group receiving epinephrine 0.2 mg/kg; 7.0 +/- 7.1 mL/min/100 g for the group receiving phenylephrine 0.1 mg/kg; and 36.7 +/- 21.1 mL/min/100 g for the group receiving phenylephrine 1.0 mg/kg.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗